If you get accused of any domestic violence, true or false, Brady says you can't posses a firearm. Another career ender.

While I see how a cop's career would end after a accusation, there's a little more than that to make you a "prohibited person" under the law. Not counting temporary restrictions on possession when under a domestic restraining order, someone has to be convicted of domestic violence before there is a permanent bar to possession.

Even if the case is dismissed and even if the accuser is convicted of perjury, the bureaucrats are going to be afraid of it being in the news if the cop is later involved in a high-profile incident such as a shooting.

They are afraid of this:

In addition to being an aspiring "rapper" (who's mother attests was "a good boy, and he was just getting his life together") the dead man was shot by a policeman who has a domestic violence complaint on his record.